The US Federal Communications Committee (FCC) specifies that a device for sensing a TV white space band should be able to detect a wireless microphone signal of signal strength −107 dbm. In case of such low signal strength, narrow-band interference caused by stray radiation, leakage, cross-modulation and the like is similar to the microphone signal. The conventional detection methods cannot distinguish the wireless microphone signal from the narrow-band interference, leading to a high false alarm rate and thus a significant decrease in the number of available TV white space bands.